From 0bdbd0e88cf6b603a2196418672715b0890fb040 Mon Sep 17 00:00:00 2001 From: Doug Anderson Date: Fri, 20 Feb 2015 12:31:56 -0800 Subject: [PATCH] mmc: dw_mmc: Don't start commands while busy We've seen problems on some WiFi modules where we seem to send a CMD53 (which requires the data lines) while the module is asserting busy. We shouldn't do that. The Designware Databook says that before issuing a new data transfer command we should check for busy, so that's what we'll do. We'll leverage the existing dw_mmc knowledge about whether it should wait for the previous command to finish to know whether we should check for busy before sending the command. This means we won't end up incorrectly waiting for things like CMD52 (SDIO) or CMD13 (SD) which don't use the data line. Note that this also has the advantage of making sure that we don't change the clock while the card is busy, too. Signed-off-by: Doug Anderson Tested-by: Javier Martinez Canillas Signed-off-by: Jaehoon Chung Signed-off-by: Ulf Hansson --- drivers/mmc/host/dw_mmc.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index d7fca9d..28fb550 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -102,6 +102,7 @@ struct idmac_desc { static bool dw_mci_reset(struct dw_mci *host); static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset); +static int dw_mci_card_busy(struct mmc_host *mmc); #if defined(CONFIG_DEBUG_FS) static int dw_mci_req_show(struct seq_file *s, void *v) @@ -335,6 +336,31 @@ static u32 dw_mci_prep_stop_abort(struct dw_mci *host, struct mmc_command *cmd) return cmdr; } +static void dw_mci_wait_while_busy(struct dw_mci *host, u32 cmd_flags) +{ + unsigned long timeout = jiffies + msecs_to_jiffies(500); + + /* + * Databook says that before issuing a new data transfer command + * we need to check to see if the card is busy. Data transfer commands + * all have SDMMC_CMD_PRV_DAT_WAIT set, so we'll key off that. + * + * ...also allow sending for SDMMC_CMD_VOLT_SWITCH where busy is + * expected. + */ + if ((cmd_flags & SDMMC_CMD_PRV_DAT_WAIT) && + !(cmd_flags & SDMMC_CMD_VOLT_SWITCH)) { + while (mci_readl(host, STATUS) & SDMMC_STATUS_BUSY) { + if (time_after(jiffies, timeout)) { + /* Command will fail; we'll pass error then */ + dev_err(host->dev, "Busy; trying anyway\n"); + break; + } + udelay(10); + } + } +} + static void dw_mci_start_command(struct dw_mci *host, struct mmc_command *cmd, u32 cmd_flags) { @@ -345,6 +371,7 @@ static void dw_mci_start_command(struct dw_mci *host, mci_writel(host, CMDARG, cmd->arg); wmb(); + dw_mci_wait_while_busy(host, cmd_flags); mci_writel(host, CMD, cmd_flags | SDMMC_CMD_START); } @@ -876,6 +903,7 @@ static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg) mci_writel(host, CMDARG, arg); wmb(); + dw_mci_wait_while_busy(host, cmd); mci_writel(host, CMD, SDMMC_CMD_START | cmd); while (time_before(jiffies, timeout)) { -- 2.7.4